Ok simple stupid easy question to the eggheads, got a little project here and need to modify a molex drive connector from my PSU to power a 12 volt item, which is the 12V lead, the yellow or the red ? Thanks in advance and yeah, I know silly stupid easy question and no, I don't have a multimeter handy !

Thanks folks....got the data I needed from you guys n gals.....off to mod up something cool.....well not really that cool...re-using a couple of fans from a PSU that went south (big burnt up coil !)....as case fans.....real interesting stuff....not.

For those who want to know how the PSU burned up, take an Athon X2 7750 overclocked to 3.1Ghz, throw in a 7950 GX2 and a woefully inadequate PSU that was rated at 500 watts and she burns up nicely.

The reason I ask, is because you CAN get 7 volts, but you don't use both the red and yellow wires. You use the yellow wire, and the 5v GROUND. NOT the red and yellow wires together. I'd hate for someone to attempt what he said and see sparks.

The reason I ask, is because you CAN get 7 volts, but you don't use both the red and yellow wires. You use the yellow wire, and the 5v GROUND. NOT the red and yellow wires together. I'd hate for someone to attempt what he said and see sparks.

You may be *correct* on the wire situation but if it is 5v it isn't ground. Ground = 0v.

I only mentioned that because I used a similar principal with the turn signals on my car. The side markers are connected to two positive voltage wires (damn near 100 certain they are anyway). Enabling them to flash in alternating sequence with the front turn signals. This was not a factory configuration, something I re-wired.

As an aside, you can get 7 volts from the +5 V and +12 V outputs -- the +5 V is considered the negative (GND) and +12 the positive -- some geeks will use this combination to run their fans at a lower speed to reduce noise.

Therefore the Red wire is +5 Volts with respect to Common and the Yellow wire is +12 Volts with respect to Common. However the Yellow wire is only +7 Volts with respect to the Red wire as the delta between +5 and +12 is +7 with the Red wire serving as the Common to the Yellow wire. Algebra says so .

The problem with playing the 7 Volt fan game is it is easy to get confused and short your PSU. The common everyone loves to use is not used.

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